Question

Statement related to center of gravity that is incorrect is
A. The center of gravity of an object is defined as the point through which its whole weight appears to act.
B. The center of gravity is sometimes confused with the center of mass.
C. The center of gravity always lies inside the object.
D. For an object placed in a uniform gravitational field, the center of gravity coincides with the center of mass.

Answer 1

Hint: The center of gravity of a system or a body is the imaginary point of the system where all the weight of the system is concentrated. The center of mass of a system or a body is the imaginary point of the system where all the mass weight of the system is concentrated. These two points may or may not be the same in the system.

Complete answer:
Center of gravity is the point on the system, around which all of its mass seems to disperse evenly and is the hypothetical point where the gravitational force is acted upon. Center of gravity of a body is the point where the whole of the weight of the body is appeared to be presented.

Center of gravity is sometimes at the same place where the center of mass of the system is present at. Center of mass of a body is the point where all of the mass of the body is concentrated at. In many cases, the center of gravity and the center of mass is at the same place, for example, when a cubic block is on a smooth surface under the constant gravitational field of the earth. Now, for a ring under constant gravity, the center of gravity lies at the center of the ring which is outside the ring.

Hence, here, option C is the correct answer.

Note:There are some other instances as well where the center of gravity may not lie inside the object such as a toroid or a solenoid. In the case of ring, toroid as well as solenoid, the center of mass generally coincides with the center of mass of the system. The center of gravity for a human body is below the stomach and near the waistline.